Electromagnetic Induction

A long solenoid has 500 turns. When a current of 2 ampere is passed through it, the resulting magnetic flux linked with each turn of the solenoid is 4 x 10⁻³ Wb. The self-inductance of the solenoid is

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The self-inductance of a coil having 500 turns is 50 mH. The magnetic flux through the cross-sectional area of the coil while current through it is 8 mA is found to be

The phase difference between the flux linked with a coil rotating in a uniform magnetic field and induced emf produced in it is

Changing magnetic fields can set up current loops in nearby metal bodies and the currents are called as

The identical loops of copper and aluminium are moving with the same speed in a magnetic field. Which of the following statements is true?

Large transformers, when used for some time, become hot and are cooled by circulating oil. The heating of transformer is due to

The initial rate of increase of current, when a battery of emf 6 V is connected in series with an inductance of 2H and resistance 12Ω, is

Find out the e.m.f. produced when the current changes from 0 to 1 A in 10 sec. Given L=10 µH.

A very small circular loop of radius a is initially (at t=0) coplanar and concentric with a much larger fixed circular loop of radius b. A constant current I flows in the larger loop. The smaller loop is rotated with a constant angular speed ω about the common diameter. The emf induced in the smaller loop as a function of time t is

Magnetic flux φ (in weber) linked with a closed circuit of resistance 10 Ω varies with time t (in sec) as φ=5t²-4t+1. The induced e.m.f. in the circuit at 0.2 sec is

The current in a self-inductance L = 40 mH is to be increased uniformly from 1A to 11A in 4 ms. The emf induced in the inductor during the process is

If a charge in current of 0.01 A in one coil produces a change in magnetic flux of 1.2 x 10⁻² Wb in the outer coil, then the mutual inductance of the coils in henry is

The induced emf in a coil of 10 H inductance in which current varies from 9 A to 4 A in 0.2 s is

Two identical circular coils A and B are kept on a horizontal tube side by side without touching each other. If the current in the coil A increases with time, in response, the coil B

When a magnet is taken towards a coil, the induced e.m.f. depends on

An average induced e.m.f. of 1 V appears in a coil when the current in it is changed from 10 A in one direction to 10A in opposite direction in 0.5 sec. Self inductance of the coil is

Two coils have the mutual inductance of 0.05 H. The current changes in the first coil as I=I₀ sin ωt, where I₀=1 A and ω=100π rad/s. The maximum emf induced in secondary coil is

If emf induced in a coil is 2 V by changing the current in it from 8 A to 6 A in 2 x 10⁻³ s, then the coefficient of self-induction is

In circular coil, when number of turns is doubled and resistance becomes 1/4th of initial value, the inductance becomes

A wire of length 1 m is moving at a speed of 2 ms⁻¹ perpendicular to its length in a homogeneous magnetic field of 0.5 T. If the ends of the wire are joined to a circuit of resistance 6Ω, then the rate at which work is being done to keep the wire moving at constant speed is

Two circuits have a mutual inductance of 0.1 H. What average e.m.f. is induced in one circuit when the current in the other circuit changes from 0 to 20 A in 0.02 s?

The self induced e.m.f. in a 0.1 H coil when the current in it is changing at the rate of 200 amp/sec is

An oscillator circuit consists of an inductance of 0. mH and a capacitor of 20 μF. The resonant frequency of the circuit is nearly

In a primary coil 5 A current is flowing on 220 V. In the secondary coil 2200 V are produced. Ratio of number of turns in secondary coil and primary coil will be

The coefficient of mutual inductance of two coils is 6 mH. If the current flowing in one is 2A, the induced e.m.f. in the second coil will be

The magnetic flux linked with a circuit of resistance 100Ω increases from 10 to 60 Wb. The amount of induced charge that flows in the circuit is (in coulomb)

Radio frequency choke uses core of

The material suitable for making electromagnets should have

In an LCR circuit, capacitance is changed from C to 2C. For the resonant frequency to remain unchanged, the inductance should be changed from L to

Energy in a current carrying coil is stored in the form of

In an inductor when current changes from 2 A to 18 A in 0.05 sec, the e.m.f. induced is 20 V. The inductance L is

Which of the following is the function of the step-up transformer?

The current through an inductor changes from 3 A to 2 A is 1 m/s. If induced e.m.f. in inductor is 5V then L is

The core of a transformer is laminated because

A transistor-oscillator using a resonant circuit with an inductor L (of negligible resistance) and a capacitor C in series produce oscillations of frequency f. If L is doubled and C is changed to 4C, the frequency will be

The turn ratio of a transformer is 1:2. An electrolytic dc cell of emf 2 volt is connected to its primary. The output voltage is

Which wavelengths of sun is used finally as electric energy?

Two coaxial solenoids are made by winding thin insulated wire over a pipe of cross-sectional area A=10 cm² and length =20 cm. If one of the solenoids has 300 turns and the other 400 turns, their mutual inductance is (μ₀=4π x 10⁻⁷ T mA⁻¹)

The flux linked with a circuit is given by φ=t³+3t-7. The graph between time (x-axis) and induced emf (y-axis) will be a

If the self inductance of 500 turn coil is 125 mH, then the self inductance of similar coil of 800 turns is

A transformer rated at 10 kW is used to connect a 5 kV transmission line to a 240 V circuit. The ratio of turns in the windings of a transformer